Ship defense requires 10kW-100kW near diffraction-limited lasers with optimal wavelength and temporal format, taking into account laser efficiency and beam quality, atmospheric transmission, thermal-blooming, and target interactions. Solid-state lasertechnology is most mature at 1mm wavelength, but 1.6mm lasers typically provide better atmospheric transmission in the marine environment. CW and high peak power laser lasers are each likely to be optimal for different targets and differentthermomechanical interactions. With current solid-state slab laser technology, 1-5kW average output power can be achieved in pulsed or CW mode at 1 micron, but typically with modest efficiency and >2x diffraction limited beam quality from a bulky system.Heat capacity lasers can achieve > 10kW power, but only for very low duty cycles. CTI proposes a breakthrough laser architecture (validated in proof-of-concept demonstrations) to enable development of compact, power-scalable MOPA systems. Thearchitecture implements a proprietary technology for achieving higher efficiencies than rod or slab architectures, with near diffraction-limited beam quality and minimal thermo-optic aberrations. Modeling indicates that using this technology, a singleMOPA system can reach 1-10kW-class power levels. Higher powers can be achieved using a phased array of these MOPAs. Phase 1 provides laser and system modeling and design trades for different gain media, wavelengths, and Navy tactical scenarios. Thiswill ensure a low risk Phase 2 program that focuses on developing a 0.5-1kW (wavelength-dependent) MOPA system, and generates designs for a >10kW system. The program will leverage CTI's experience in kW-class lasers and in flight qualified laser systems.In addition to DoD directed energy applications, high brightness, high average power solid state lasers are required for applications in materials processing in semiconductor manufacturing and in automotive and aircraft industries, and for destruction ofused surface ordnance.